Plastic containers or bottles are prevalent today in a wide variety of shapes and sizes for holding many different kinds of materials such as light duty liquids (e.g., dishwashing detergent), heavy duty liquids (e.g., laundry detergents), motor oil, vegetable oil, herbicides, etc. Generally, these containers are fabricated from layers or a plurality of layers of plastic, particularly polypropylene, polyethylene and polyesters, by means of blow molding or injection molding.
Generally, such containers are provided with a label which designates the trade name of the product and may contain other information as well. In some instances, the label is merely attached to the container after molding by means of adhesive or the like. However, the label may also be attached to the container during the container molding process. This technology by which the label is associated with the container during the molding operation is generally referred to as an in-mold label process.
Methods and articles describing same are known for performing in-mold labeling of a plastic container. For example, Dronzek, Jr., U.S. Pat. Nos. 5,711,839 and 5,925,208, in the name of one of the applicants herein, and commonly assigned, teach that polymeric sheets or rolls suitable for printing and forming, at high rates of production, blown or injection in-mold labeled plastic containers if made from a polymeric transparent, translucent or contact clear substrate, preferably monoaxially or biaxially oriented, and having a thickness in the range of 0.002 to 0.008 inches which is reverse printed and overcoated on the container-facing side with a heat activatable adhesive and coated or extruded on the opposite side with an antistatic and/or slip coating. Optionally, these Patents teach that such sheets or rolls can be printed and then cut into individual labels for affixing to the container as part of an in-molding process. Recyclable containers are provided at high speed without missing labels or doubled labels due to feeding problems. The labels are firmly adherent, and squeeze-release resistant and the indicia, because they are viewable through the labels themselves, are protected against spillage and abrasion.
Also relevant for its teachings, regarding in-mold labeling with a removable coupon portion, is Sullivan et al, U.S. Pat. No. 5,172,936, the label having a permanent portion and a removable portion, a printed face, and an adhesive-coated back, the permanent areas of the label having a degree of adhesion resulting in a permanent bond and the removable areas being covered with an adhesive with a lower degree of adhesion so as to allow the removable portion to be removed from the surface. The labels provided by the teachings of U.S. Pat. No. 5,172,936 are not made by a process which uses, as its final step, overcoating the patterned adhesive with the permanent adhesive. Moreover the removable portions are disclosed to tend to wrinkle, crease and blister. It would be desirable to eliminate such shortcomings, while at the same time providing a coupon which is different in use and appearance, but maintains all functional advantages.
Also relevant for its teachings with respect to machine-direction oriented label films and die-cut labels prepared therefrom is Josephy et al, U.S. Pat. No. 5,585,193, which discloses labels prepared from a multilayer composite cast extruded and oriented in the machine direction. The composite also comprises an adhesive layer for adhering the label to a substrate. The advantage provided by such composites is improved die-cuttability.
The present state of the art thus shows that white opaque, transparent, translucent, clear or contact clear polymeric films having judiciously selected characteristics of thickness, specific gravity and coefficient of expansion and contraction and provided with a heat activatable adhesive coating have improved and surprising characteristics of adhesion to in-mold blown plastic containers with resistance to damage from cracking, tearing, creasing, wrinkling or shrinking due to physical abuse and flexing of the plastic container material. Furthermore, it has been shown in U.S. Pat. No. 5,192,936 that labels with removable coupons can be provided from polymeric face stock by pattern printing with a permanent adhesive the area to be permanently affixed and pattern-printing with a lesser strength adhesive with selectively removable features under the coupon-removable area. This patent teaches the use of less adhesive, a different adhesive or a modified adhesive to achieve the desired objectives. In addition, the prior art teaches, in U.S. Pat. No. 5,585,193, that using a machine-direction oriented film improves the die-cuttability of labels prepared from such films.
It has now been found that making an in-mold label having a removable coupon portion is unexpectedly improved if the film used is oriented uniaxially in the machine direction and is axially in line with the direction of tear when the coupon is ultimately removed.
It has also been found that the process for making the labels with removable features is simplified, and an improved coupon is obtained, if a patterned “abhesive” (i.e., an anti-adhesive; non-stick, anti-adherent properties) is laid down on the substrate in the shape of the coupon and the entire side facing the in-mold article is overcoated with the permanent adhesive to insure that there is no wrinkling or creasing in the removable area making a permanent bond between the adhesive and the container interface.
Accordingly, a principal object of the present invention is to provide for the use of surface- or backside-printable polymeric sheets or rolls to make labels for in-mold use without the problems discussed above. It is a further object of the invention to provide a method for in-mold labeling of hollow plastic containers using printed labels made from such sheets. It is still another object of the invention to provide articles labeled with printed labels which have the unexpectedly superior properties described above.
These and other objects of the invention will become apparent from the present specification.